In continuous casting of metals such as brass and the like, it is common to permit molten metal to flow from a crucible through a die which is surrounded by a cooling apparatus so that the molten metal progressively solidifies and is withdrawn by suitable apparatus. A major consideration in the efficiency of such a device is the ability to remove heat from the die.
In my U.S. Pat. No. 4,151,765, an efficient apparatus for cooling the die is shown which utilizes a cooling sleeve having intimate contact with the exterior surface of the die, which cooling sleeve is externally cooled by flowing coolant about the periphery thereof. Inasmuch as the coolant that first contacts the cooling sleeve is cold and progressively increases in temperature, there is a tendency for the cooling sleeve to be cooled unevenly and expand out of intimate contact with the die.
Among the objects of the present invention are to provide an improved die and cooling assembly which will efficiently cool and thereby increase the efficiency of the continuous casting apparatus and the quality of the products.
In my copending application Ser. No. 258,590, filed Apr. 29, 1981, abandoned, the die and cooling assembly comprises a tubular die having an external tapered surface which is uniformly tapered radially inwardly in the direction of movement to the die, a cooling sleeve having an internal surface complementary to the external surface of the die and in substantial intimate contact with the external surface of the die, an annular cooling jacket wall surrounding the cooling sleeve and having portions thereof spaced from the sleeve to define a cooling chamber, at least one coolant inlet to said chamber and at least one coolant outlet from said chamber. The inlet and outlet are spaced axially with the outlet being nearest the upper end of the die where the molten metal enters the die and the inlet being nearest the lower end of the die where the solidified metal leaves the die. The cooling sleeve preferably has a plurality of circumferentially spaced integral ribs extending radially outwardly therefrom into close proximity to the inner surface of the cooling jacket such that coolant flows in a thin layer along the inner surface of the cooling jacket and in a plurality of axial paths along the surfaces of the ribs. The ribs are of progressively increasing height circumferentially about the cooling sleeve from the area of the coolant inlet to the area of the coolant outlet.
In certain situations, to increase production to a maximum uniformly greater heat transfer is required. For example, wherein the cross section of the continuous part being made is non-uniform, the die has a varying thickness so that problems arise not only during the casting operation but in the resultant product causing weakness in the final structure, separation of the components of the alloy, non-uniform molecular structure and fractures on the cast products.
Accordingly, the objects of the invention are to provide an improved die and cooling assembly which will efficiently cool the die in situations wherein unusual and excessive heat is present and where the circumferential portions of the die may vary in temperature.
In accordance with the invention the cooling sleeve has a plurality of axially extending circumferentially spaced openings positioned intermediate the inner and outer surfaces thereof and a first set of radial passages extends from the lower end of the cooling chamber to the axial openings and a second set of radial passages extends from the upper end of the axial passages to the chamber and, in turn, said outlet.